Organic light emitting diode display

ABSTRACT

An organic light emitting diode (OLED) display according to an exemplary embodiment includes: a substrate including a display area for displaying an image and a transmissive area around the display area; an insulating layer formed on the transmissive area of the substrate; and a pixel definition layer formed on the substrate and defining a pixel area within the display area. The pixel definition layer may cover an inner circumferential surface of a transmissive hole formed in the insulating layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

This application claims priority to and the benefit of Korean PatentApplication No. 10-2015-0019674 filed in the Korean IntellectualProperty Office on Feb. 9, 2015, the entire contents of which areincorporated herein by reference.

BACKGROUND

1. Field

The present disclosure relates to an organic light emitting diode (OLED)display, and more particularly, to a transparent OLED display.

2. Description of the Related Technology

Currently, as generally known display devices, there are a liquidcrystal display (LCD), a plasma display panel (PDP), an organic lightemitting diode (OLED) display, a field effect display (FED), anelectrophoretic display, and the like.

Particularly, the OLED display includes two electrodes and an organicemission layer interposed therebetween, and emits light by combiningelectrons injected from one electrode and holes injected from the otherelectrode in the organic emission layer to generate excitons and usingenergy released by the excitons.

The OLED display may have a reduced thickness and weight since it has aself-luminance characteristic and does not require an additional lightsource, unlike the LCD.

In addition, the OLED display is receiving attention as a nextgeneration display device since it represents high qualitycharacteristics such as low power consumption, high luminance, and highresponse speed.

Recently, a display device formed with a transmissive area adjacent toan organic light emitting element where external light is transmitted isbeing developed.

The display device formed with the transmissive area is recognized as anoverall transparent display device.

However, the external light is scattered to cause transmittance of thetransmissive area to deteriorate when it passes through the transmissivearea.

SUMMARY

An exemplary embodiment has been made in an effort to provide atransparent organic light emitting diode (OLED) display that is capableof preventing external light from being scattered in a transmissivearea.

An OLED display according to an exemplary embodiment includes: asubstrate including a display area for displaying an image and atransmissive area around the display area; an insulating layer formed onthe transmissive area of the substrate; and a pixel definition layerformed on the substrate and defining a pixel area within the displayarea. The pixel definition layer covers an inner circumferential surfaceof a transmissive hole formed in the insulating layer.

The pixel definition layer may include an insulating material and alight blocking material.

The insulating material may include at least either one of a polyamideand a resin based on polyacrylates, polyimides, or siloxanes.

The light blocking material may include a black coloring agent.

The substrate may be a transparent substrate.

A common electrode may be positioned on the pixel definition layerwithin the transmissive area of the substrate.

The common electrode may be a transparent electrode.

The OLED display may further include an organic light emitting elementpositioned on the display area of the substrate.

The OLED display may further include a thin film transistor that ispositioned between the substrate and the organic light emitting elementand connected to the organic light emitting element.

The thin film transistor may further include an active layer positionedon the substrate.

The thin film transistor may include: an active layer positioned on thesubstrate; a gate electrode positioned on the active layer; and sourceand drain electrodes positioned on the gate electrode and connected tothe active layer.

The organic light emitting element may include: a first electrodeconnected to the drain electrode of the thin film transistor; an organicemission layer positioned on the first electrode; and a second electrodepositioned on the organic emission layer.

The insulating layer may include: a first insulating layer covering thesource and drain electrodes; and a second insulating layer formed on thefirst insulating layer, and the pixel definition layer covers the secondinsulating layer and the first electrode.

The insulating layer may include a first insulating layer that coversthe source and drain electrodes, and the pixel definition layer coversthe first insulating layer and the first electrode.

According to the exemplary embodiment, scattering of the external lightin the transmissive area can be prevented to increase transparency ofthe transparent display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a layout view of an organic light emitting diode (OLED)display according to an exemplary embodiment.

FIG. 2 is an equivalent circuit diagram of one pixel of the OLEDdisplay.

FIG. 3 is a layout view of one pixel of the OLED display according tothe an exemplary embodiment.

FIG. 4 is a cross-sectional view of the display device of FIG. 3 takenalong the line IV-IV.

FIG. 5 is a cross-sectional view of the display device of FIG. 3 takenalong the line V-V.

FIG. 6 is a cross-sectional view of a display device according to asecond exemplary embodiment taken along the line V-V of FIG. 3.

DETAILED DESCRIPTION

As the disclosure allows for various changes and numerous embodiments,particular embodiments will be illustrated in the drawings and describedin detail in the written description. However, this is not intended tolimit the present disclosure to particular modes of practice, and it isto be appreciated that all changes, equivalents, and substitutes that donot depart from the spirit and technical scope of the present disclosureare encompassed in the present disclosure. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Embodiments of the present disclosure will be described below in moredetail with reference to the accompanying drawings. Those componentsthat are the same or are in correspondence are rendered the samereference numeral regardless of the figure number, and redundantexplanations are omitted.

It will be understood that although the terms “first”, “second”, etc.may be used herein to describe various components, these componentsshould not be limited by these terms. These components are only used todistinguish one component from another.

As used herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising” used herein specify the presence of stated featuresor components, but do not preclude the presence or addition of one ormore other features or components. In the drawings, the thickness oflayers, films, panels, regions, etc., are exaggerated for explanation.In other words, since sizes and thicknesses of components in thedrawings are arbitrarily illustrated for convenience of explanation, thefollowing embodiments are not limited thereto. Like reference numeralsdesignate like elements throughout the specification. It will beunderstood that when an element such as a layer, film, region, orsubstrate is referred to as being “on” another element, it can bedirectly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” another element, there are no intervening elements present.

In addition, when a layer is described to be formed “on” another layeror substrate, this means that the layer may be formed directly on theother layer or substrate, or a third layer may be interposed between thelayer and the other layer or the substrate.

Like reference numerals designate like elements throughout thespecification.

An organic light emitting diode (OLED) display according to a firstexemplary embodiment will now be described with reference to FIGS. 1 to5.

As shown in FIGS. 1 to 5, in the OLED display according to the exemplaryembodiment, which is a transparent display device transparentlyperceived by light transmitted through a transmissive area TA, an innercircumferential surface of a transmissive hole 400 formed in thetransmissive area TA may be covered by a pixel definition layer of ablack-series color to prevent scattering of light.

Accordingly, transmittance of light in the transmissive area TA mayincrease to improve sharpness of the transparent display device.

Referring to FIG. 1, the OLED display according to the first exemplaryembodiment includes a display area PA including a plurality of subpixelsPX1, PX2, and PX3, and a transmissive area TA formed around the displayarea PA.

Each of the plurality of subpixels PX1, PX2, and PX3 in the display areaPA includes an organic light emitting element 70, thin film transistorsT1 and T2, etc.

In addition, the transmissive area TA corresponds to a region whereexternal light is transmitted through the transmissive hole 400.

As the external light is transmitted through the transmissive area TA,the transparent display device is perceived as an overall transparentone.

First, referring to FIGS. 2 to 4, one subpixel of the display area PAwill now be described in detail.

Referring to FIG. 2, the OLED display includes a plurality of signallines 121, 171, and 172, and pixels PX connected thereto.

In this case, the pixels PX may be any one of a red pixel PX1, a greenpixel PX2, and a blue pixel PX3.

The signal lines include gate lines 121 for transmitting a scanningsignal, data lines 171 for transmitting a data signal, a driving voltageline 172 for transmitting a driving voltage, and the like.

The gate lines 121 substantially extend in a row direction and arenearly parallel to each other, while the data lines 171 substantiallyextend in a column direction and are nearly parallel to each other.

The driving voltage lines 172 are illustrated to substantially extend inthe column direction, but they may extend in the row or column directionor have a net-like shape.

In this case, one pixel PX includes a thin film transistor including aswitching transistor T1 and a driving transistor T2, a storage capacitorCst, and an organic light emitting element LD.

Though not illustrated in the drawings, one pixel PX may further includea thin film transistor and a capacitor to compensate a current that issupplied to the organic light emitting element LD.

The switching transistor T1 includes a control terminal N1, an inputterminal N2, and an output terminal N3.

In this case, the control terminal N1 is connected to the gate line 121,the input terminal N2 is connected to the data line 171, and the outputterminal N3 is connected to the driving transistor T2.

The switching transistor T1 transmits the data signal transmitted viathe data line 171 to the driving transistor T2 in response to thescanning signal transmitted via the gate line 121.

The driving transistor T2 also includes a control terminal N3, an inputterminal N4, and an output terminal N5.

In this case, the control terminal N3 is connected to the switchingtransistor T1, the input terminal N4 is connected to the driving voltageline 172, and the output terminal N5 is connected to the organic lightemitting element LD.

The driving transistor T2 outputs an output current Id, a magnitude ofwhich varies according to a voltage applied between the control terminalN3 and the output terminal N5.

In this case, the capacitor Cst is connected between the controlterminal N3 and the input terminal N4 of the driving transistor T2.

The capacitor Cst is charged with a data signal applied to the controlterminal N3 of the driving transistor T2, and maintains the data signaleven after the switching transistor T1 is turned off.

For example, as an organic light emitting diode (OLED), the organiclight emitting element LD has an anode connected to the output terminalN5 of the driving transistor T2 and a cathode connected to a commonvoltage Vss.

The organic light emitting element LD displays an image by emittinglight of varying intensities according to the output current Id of thedriving transistor T2.

The organic light emitting element LD may contain an organic materialthat represents one or more of primary colors including three thereofsuch as red, green, and blue, and the OLED display displays a desiredimage with a spatial sum of these colors.

The switching transistor T1 and the driving transistor T2 are n-channelelectric effect transistors (FETs), but at least one of them may be ap-channel FET.

In addition, a connection relationship between the transistors T1 andT2, the capacitor Cst, and the organic light emitting element LD may bechanged.

A structure of the OLED display according to the first exemplaryembodiment will now be described in detail with reference to FIGS. 3 to5.

Referring to FIG. 4, a substrate 110 may be formed as an insulatingsubstrate that is formed of glass, quartz, ceramic, plastic, etc.

A buffer layer 120 is formed on the substrate 110.

The buffer layer 120 may be formed as a single layer of a siliconnitride (SiN_(x)) or as a dual-layer in which a silicon nitride(SiN_(x)) and a silicon oxide (SiO_(x)) are laminated.

The buffer layer 120 serves to planarize a surface while preventingpermeation of unnecessary materials such as impurities or moisture.

A switching semiconductor layer 135 a and a driving semiconductor layer135 b are formed on the buffer layer 120 to be separated from eachother.

These semiconductor layers 135 a and 135 b may be formed of polysiliconor an oxide semiconductor.

In this case, the oxide semiconductor may include one of oxides based ontitanium (Ti), hafnium (Hf), zirconium (Zr), aluminum (Al), tantalum(Ta), germanium (Ge), zinc (Zn), gallium (Ga), tin (Sn), or indium (In),and complex oxides thereof such as zinc oxide (ZnO), indium-gallium-zincoxide (InGaZnO₄), indium-zinc oxide (Zn—In—O), zinc-tin oxide (Zn—Sn—O),indium-gallium oxide (In—Ga—O), indium-tin oxide (In—Sn—O),indium-zirconium oxide (In—Zr—O), indium-zirconium-zinc oxide(In—Zr—Zn—O), indium-zirconium-tin oxide (In—Zr—Sn—O),indium-zirconium-gallium oxide (In—Zr—Ga—O), indium-aluminum oxide(In—Al—O), indium-zinc-aluminum oxide (In—Zn—Al—O), indium-tin-aluminumoxide (In—Sn—Al—O), indium-aluminum-gallium oxide (In—Al—Ga—O),indium-tantalum oxide (In—Ta—O), indium-tantalum-zinc oxide(In—Ta—Zn—O), indium-tantalum-tin oxide (In—Ta—Sn—O),indium-tantalum-gallium oxide (In—Ta—Ga—O), indium-germanium oxide(In—Ge—O), indium-germanium-zinc oxide (In—Ge—Zn—O),indium-germanium-tin oxide (In—Ge—Sn—O), indium-germanium-gallium oxide(In—Ge—Ga—O), titanium-indium-zinc oxide (Ti—In—Zn—O), andhafnium-indium-zinc oxide (Hf—In—Zn—O).

When the semiconductor layers 135 a and 135 b are formed of an oxidesemiconductor, a separate passivation layer may be added to protect theoxide semiconductor that is vulnerable to an external environment suchas high temperature and the like.

The semiconductor layers 135 a and 135 b include a channel region whereimpurities are not doped, and source and drain regions at opposite sidesof the channel region where the impurities are doped.

In this case, the doped impurities may be changed depending on types ofthe thin film transistors, and may be n-type or p-type impurities.

The switching semiconductor layer 135 a and the driving semiconductorlayer 135 b are divided into channel regions 1355 and source and drainregions 1356 and 1357 formed at opposite sides of the channel region1355, respectively.

The channel regions 1355 of the switching semiconductor layer 135 a andthe driving semiconductor layer 135 b may include polysilicon that isnot doped with the impurities, that is, an intrinsic semiconductor.

In addition, the source and drain regions 1356 and 1357 of the switchingsemiconductor layer 135 a and the driving semiconductor layer 135 b mayinclude polysilicon that is doped with conductive impurities, that is,an impurity semiconductor.

A gate insulating layer 140 is formed on the switching semiconductorlayer 135 a and the driving semiconductor layer 135 b.

The gate insulating layer 140 may be a single layer or multiple layersincluding at least either one of a silicon nitride and a silicon oxide.

Referring to FIG. 3, a gate line 121, a driving gate electrode 125 b,and a first capacitor electrode 128 are formed on the gate insulatinglayer 140.

The gate line 121 extends in a horizontal direction, and transmits ascan signal to a switching transistor T1.

In this case, the gate line 121 includes a switching gate electrode 125a that protrudes toward the switching semiconductor layer 135 a.

The driving gate electrode 125 b protrudes toward the drivingsemiconductor layer 135 b from the first capacitor electrode 128.

The switching gate electrode 125 a and the driving gate electrode 125 boverlap the channel region 1355, respectively.

An interlayer insulating layer 160 is formed on the gate line 121, thedriving gate electrode 125 b, and the first capacitor electrode 128.

The interlayer insulating layer 160 may be formed of a silicon nitride,a silicon oxide, or the like, as is the gate insulating layer 140.

In the interlayer insulating layer 160 and the gate insulating layer140, a source contact hole 61 and a drain contact hole 62 are formed torespectively expose the source region 1356 and the drain region 1357,and a storage contact hole 63 is formed to expose some of the firstcapacitor electrode 128.

A data line 171 having a switching source electrode 176 a, a drivingvoltage line 172 having a driving source electrode 176 b and a secondcapacitor electrode 178, and a switching drain electrode 177 a and adriving drain electrode 177 b connected to the first capacitor electrode128 are formed on the interlayer insulating layer 160.

The data line 171 transmits a data signal, and extends to cross the gateline 121.

The driving voltage line 172 transmits a driving voltage, and isseparated from the data line to extend in the same direction as the dataline 171.

The switching source electrode 176 a protrudes toward the switchingsemiconductor layer 135 a from the data line 171, and the driving sourceelectrode 176 b protrudes toward the driving semiconductor layer 135 bfrom the driving voltage line 172.

The switching source electrode 176 a and the driving source electrode176 b are connected to the source region 1356 through the source contacthole 61, respectively.

The switching drain electrode 177 a faces the switching source electrode176 a, and the driving drain electrode 177 b faces the driving sourceelectrode 176 b.

In addition, the switching drain electrode 177 a and the driving drainelectrode 177 b are connected to the drain region 1357 through the draincontact hole 62, respectively.

The switching drain electrode 177 a is extended to be electricallyconnected to the first capacitor electrode 128 and the driving gateelectrode 125 b through the contact hole 63 formed in the interlayerinsulating layer 160.

The second capacitor electrode 178 protrudes from the driving voltageline 172 to overlap the first capacitor electrode 128.

Accordingly, the first capacitor electrode 128 and the second capacitorelectrode 178 form the storage capacitor Cst using the interlayerinsulating layer 160 as a dielectric material.

The switching semiconductor layer 135 a, the switching gate electrode125 a, the switching source electrode 176 a, and the switching drainelectrode 177 a form a switching thin film transistor T1.

Meanwhile, the driving semiconductor layer 135 b, the driving gateelectrode 125 b, the driving source electrode 176 b, and the drivingdrain electrode 177 b form a driving thin film transistor T2.

The switching thin film transistor T1 and the driving thin filmtransistor T2 correspond to switching elements.

A passivation layer 180 is formed on the switching source electrode 176a, the driving source electrode 176 b, the switching drain electrode 177a, and the driving drain electrode 177 b.

According to the an exemplary embodiment, a lower passivation layer 170may be formed under the passivation layer 180.

In this case, the lower passivation layer 170 may be disposed betweenthe interlayer insulating layer 160 and the passivation layer 180.

In the disclosure, the lower passivation layer 170 and the passivationlayer 180 may correspond to the same components as the first and secondinsulating layers.

A pixel electrode 710 is formed on the passivation layer 180.

In this case, the pixel electrode 710 may be formed of a transparentconductive material such as indium tin oxide (ITO), indium zinc oxide(IZO), zinc oxide (ZnO), indium oxide (In₂O₃), etc., or a reflectivemetal such as lithium, calcium, lithium fluoride/calcium, lithiumfluoride/aluminum, aluminum, silver, magnesium, gold, etc.

Referring to FIGS. 3 and 5, the pixel electrode 710 is electricallyconnected to the driving drain electrode 177 b of the driving thin filmtransistor T2 through a contact hole 181 formed in the interlayerinsulating layer 160, and becomes an anode of the organic light emittingelement 70.

A pixel definition layer 350 is formed on edge portions of thepassivation layer 180 and the pixel electrode 710.

The pixel definition layer 350 includes an opening that exposes thepixel electrode 710.

According to an exemplary embodiment, the pixel definition layer 350 maybe formed of an insulating material and a light blocking material.

The light blocking material may be included in the pixel definitionlayer 350 to prevent scattering of light in a transmissive area to bedescribed later.

This will be described later in detail.

In this case, the pixel definition layer 350 may include an insulatingmaterial such as a polyamide, a resin based on polyacrylates orpolyimides, a siloxane-based resin, and a silica-based inorganicmaterial.

In addition, the light blocking material of the pixel definition layer350 may include a black coloring agent such as carbon black or titanblack.

In addition, the light blocking material may use channel black, furnaceblack, thermal black, lamp black, etc., and may use an organic pigmentsuch as a water-soluble azo pigment, a water-insoluble azo pigment, aphthalocyanine pigment, a quinacridone pigment, an isoindolinonepigment, an isoindoline pigment, a perylene pigment, a perynone pigment,a dioxazine pigment, an anthraquinone pigment, a dianthraquinonylpigment, an anthrapyrimidine pigment, an anthanthrone pigment, anindanthrone pigment, a flavanthrone pigment, a pyranthrone pigment, adiketopyrrolopyrrole pigment, etc.

An organic emission layer 720 is formed in the opening of the pixeldefinition layer 350.

The organic emission layer 720 is formed as multiple layers includingone or more of the emission layer, a hole-injection layer (HIL), ahole-transporting layer (HTL), an electron-transporting layer (ETL), andan electron-injection layer.

When the organic emission layer 720 includes all of them, the HIL ispositioned on the pixel electrode 710 serving as the anode, and the HTL,the emission layer, the ETL, and the EIL may be sequentially laminatedthereon.

The organic emission layer 720 may include a red organic emission layeremitting red light, a green organic emission layer emitting green light,and a blue organic emission layer emitting blue light. The red organicemission layer, the green organic emission layer, and the blue organicemission layer are respectively formed on a red pixel, a green pixel,and a blue pixel to implement a color image.

Further, the red organic emission layer, the green organic emissionlayer, and the blue organic emission layer are integrally laminated onthe organic emission layer 720 together with the red pixel, the greenpixel, and the blue pixel to respectively form a red color filter, agreen color filter, and a blue color filter in each pixel so as toimplement a color image.

Alternatively, a white organic emission layer emitting white light isformed on all of the red pixel, the green pixel, and the blue pixel, anda red color filter, a green color filter, and a blue color filter arerespectively formed for every pixel to implement a color image.

When the color image is implemented by using the white organic emissionlayer and the color filter, a deposition mask for depositing the redorganic emission layer, the green organic emission layer, and the blueorganic emission layer on individual pixels, that is, the red pixel, thegreen pixel, and the blue pixel, is not required.

The white organic emission layer described in another exemplaryembodiment may be formed to have a single organic emission layer, andmay further include a configuration in which a plurality of organicemission layers are laminated to emit white light.

For example, a configuration in which at least one yellow organicemission layer and at least one blue organic emission layer are combinedto emit white light, a configuration in which at least one cyan organicemission layer and at least one red organic emission layer are combinedto emit white light, and a configuration in which at least one magentaorganic emission layer and at least one green organic emission layer arecombined to emit white light may be further included.

A common electrode 730 is formed on the pixel definition layer 350 andthe organic emission layer 720.

The common electrode 730 may be made of a transparent conductivematerial such as indium tin oxide (ITO), indium zinc oxide (IZO), zincoxide (ZnO), indium oxide (In₂O₃), etc., or a reflective metal such aslithium, calcium, lithium fluoride/calcium, lithium fluoride/aluminum,aluminum, silver, magnesium, gold, etc.

The common electrode 730 becomes a cathode of the organic light emittingelement 70.

The pixel electrode 710, the organic emission layer 720, and the commonelectrode 730 form the organic light emitting element 70.

An overcoat (not shown) may be formed on the common electrode 730 toprotect the organic light emitting element 70.

Referring to FIG. 5, a transmissive hole 400 is formed in a transmissivearea TA.

As described above, external light is transmitted through thetransmissive hole 400, thereby allowing the OLED display to be perceivedas a transparent display device.

In this case, the transmissive hole 400 is formed in the transmissivearea TA to penetrate the laminated insulating layers and the like.

In FIG. 5, the substrate 110 is exposed by the transmissive hole 400.

However, it is not limited thereto, and the insulating layer may bepositioned on the substrate 110 and the insulating layer may be exposedby the transmissive hole 400.

However, the insulating layer and the substrate 110 may be transparent.

Meanwhile, the passivation layer 180, the lower passivation layer 170,the interlayer insulating layer 160, the gate insulating layer 140, andthe buffer layer 120 may be penetrated by the transmissive hole 400.

However, as described above, only some of the plurality of layers may bepenetrated by the transmissive hole 400.

However, the layers that are not penetrated may be transparently formed.

According to an exemplary embodiment, the pixel definition layer 350covers an inner circumferential surface of the transmissive hole 400.

In this case, the pixel definition layer 350 may be formed of a lightblocking material.

More specifically, as described above, the pixel definition layer 350may be formed of an insulating material and a light blocking material.

The light blocking material may be included in the pixel definitionlayer 350 to prevent scattering of light in the transmissive area.

Generally, in the transparent display device, the external lighttransmitted through the transmissive hole 400 may be scattered on theinner circumferential surface of the transmissive hole 400.

As such, when the external light is scattered, transparency of thetransparent display device deteriorates.

According to an exemplary embodiment, the inner circumferential surfaceof the transmissive hole 400 may be covered by the pixel definitionlayer 350 formed of the light blocking material, thereby preventingscattering of the external light.

In this case, the pixel definition layer 350 may include an insulatingmaterial such as a polyamide, a resin based on polyacrylates orpolyimides, a siloxane-based resin, and a silica-based inorganicmaterial.

In addition, the light blocking material of the pixel definition layer350 may include a black coloring agent such as carbon black or titanblack.

In addition, the light blocking material may use channel black, furnaceblack, thermal black, lamp black, etc., and may use an organic pigmentsuch as a water-soluble azo pigment, a water-insoluble azo pigment, aphthalocyanine pigment, a quinacridone pigment, an isoindolinonepigment, an isoindoline pigment, a perylene pigment, a perynone pigment,a dioxazine pigment, an anthraquinone pigment, a dianthraquinonylpigment, an anthrapyrimidine pigment, an anthanthrone pigment, anindanthrone pigment, a flavanthrone pigment, a pyranthrone pigment, adiketopyrrolopyrrole pigment, etc.

A common electrode 730 is formed on the pixel definition layer 350.

In this case, the common electrode 730 may be made of a transparentconductive material such as indium tin oxide (ITO), indium zinc oxide(IZO), zinc oxide (ZnO), indium oxide (In₂O₃), etc.

An OLED display according to a second exemplary embodiment will now bedescribed with reference to FIG. 6.

When describing the OLED display of the second exemplary embodiment, adetailed description of components identical or similar to those of theOLED display of the first exemplary embodiment will be omitted.

Referring to FIG. 6, in the OLED display according to the secondexemplary embodiment, the passivation layer 180 of the previousembodiment is not formed on the lower passivation layer 170.

The lower passivation layer 170 is positioned on the pixel definitionlayer 350.

The pixel definition layer 350 instead performs a function of theremoved passivation layer 180.

Therefore, the pixel definition layer 350 is formed on the lowerpassivation layer 170 to perform a planarization function.

The second exemplary embodiment differs from the first exemplaryembodiment in that the passivation layer 180 is removed and the pixeldefinition layer 350 instead performs the planarization function of thepassivation layer 180.

According to the exemplary embodiment, the inner circumferential surfaceof the transmissive hole 400 may be covered by the pixel definitionlayer 350 formed of the light blocking material, thereby preventingscattering of the external light.

It should be understood that the exemplary embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While one or more embodiments of the present disclosure have beendescribed with reference to the figures, it will be understood by thoseof ordinary skill in the art that various changes in form and detailsmay be made therein without departing from the spirit and scope of thepresent disclosure as defined by the following claims.

What is claimed is:
 1. An organic light emitting diode (OLED) displaycomprising: a substrate including a display area for displaying an imageand a transmissive area around the display area; an insulating layerformed on the transmissive area of the substrate; and a pixel definitionlayer formed on the substrate and defining a pixel area within thedisplay area, wherein the pixel definition layer covers an innercircumferential surface of a transmissive hole formed in the insulatinglayer.
 2. The OLED display of claim 1, wherein the pixel definitionlayer includes an insulating material and a light blocking material. 3.The OLED display of claim 2, wherein the insulating material includes atleast either one of a polyamide and a resin based on polyacrylates,polyimides, or siloxanes.
 4. The OLED display of claim 2, wherein thelight blocking material includes a black coloring agent.
 5. The OLEDdisplay of claim 1, wherein the substrate is a transparent substrate. 6.The OLED display of claim 1, wherein a common electrode is positioned onthe pixel definition layer within the transmissive area of thesubstrate.
 7. The OLED display of claim 6, wherein the common electrodeis a transparent electrode.
 8. The OLED display of claim 1, furthercomprising an organic light emitting element positioned on the displayarea of the substrate.
 9. The OLED display of claim 8, furthercomprising a thin film transistor positioned between the substrate andthe organic light emitting element and connected to the organic lightemitting element.
 10. The OLED display of claim 9, wherein the thin filmtransistor includes: an active layer positioned on the substrate; a gateelectrode positioned on the active layer; and source and drainelectrodes positioned on the gate electrode and connected to the activelayer.
 11. The OLED display of claim 10, wherein the organic lightemitting element includes: a first electrode connected to the drainelectrode of the thin film transistor; an organic emission layerpositioned on the first electrode; and a second electrode positioned onthe organic emission layer.
 12. The OLED display of claim 11, whereinthe insulating layer includes: a first insulating layer covering thesource and drain electrodes; and a second insulating layer formed on thefirst insulating layer, and the pixel definition layer covers the secondinsulating layer and the first electrode.
 13. The OLED display of claim11, wherein the insulating layer includes a first insulating layer thatcovers the source and drain electrodes, and the pixel definition layercovers the first insulating layer and the first electrode.